Design of an energy saving ACN-based butadiene production process by using dividing wall columns

Butadiene (normally refers to 1,3-butadiene), separated from C4 mixture, is a major petrochemical product and an important feedstock for downstream polymerization processes. Because each component of the C4 mixture has very similar relative volatilities, extractive distillation is usually used to separate butadiene from the other C4 components, with the aid of some solvents such as acetonitrile (ACN), dimethylformamide (DMF), N-methyl-2-pyrrolidone (NMP). This study considers the ACN-based butadiene production process, which contains several extractive distillation columns (EDCs) and conventional distillation columns (CDiCs). To obtain an energy saving process, the concept of dividing wall column (DWC) is introduced to redesign the conventional flowsheet. That is, two EDCs and two CDiCs are replaced by an extractive dividing wall column (EDWC) and a simple DWC, respectively. With using Aspen Plus, it is observed that the new process design requires less energy consumption as well as less space than the conventional design.